Can't find any reason for that noise.

jboz

Hi guys. Well, I took everbody's suggestions trying to track down that chain-like slapping noise within my 426. Everything looks great on the just under the surface.

1st - I've had everybody who's anybody listen to it including a coupla bike mechanics. No idea - maybe a piece of clutch floating around, cam chain.... The noise is intermitant at idle - just a little rattle every second or 2. I had one mechanic ride it - I could hear it as he was slowly accelerating away; he looked back at me & immediatley turned around & came back. It's pronounced. And it doesn't matter whether the clutch is in or not. The clutch is very grabby, but had plenty of oil, no dry plates at all.

I've pulled the clutch & basket. Plates are fine, all clutch plates are within spec & none are damaged. The gears & such behind look like a new baby's bottom. Perfect. Pulled the ignition cover off & strained oil thru a paper towel. Every thing looks fine & nothing in the oil. Pulled valve cover off & valves are within spec to the tight side. Cam chain looks fine, when I rotate the engine & move it back & forth I can see no slack in it. Shine a flashlight down & bottom gear looks ok, chain is tight against adjuster. The front of the chain though is riding the slider all the way down, it doesn't look loose or out of place, but it is definately maiking the chain belly in a little.

Any more ideas? I talked to the mechanic at my dealer & he's never had a 4 stroker apart ("Geeze, I've never heard of anyone having a problem w/ a 400/426") But he's real interested in checking one out... I'd rather it not be on mine!

Guest_Guest_*

jboz
I had a similar noise and it turned out to be a missing tooth off 4th gear. However, you would hear the "chain rattle noise" in all the gears. When I got the 4th gear the klunking noise was more pronounced.

426's are notorious for bad 4th gears. I hope this is not what your problem is.

Guest_Guest_*

I have encountered a problem on two bikes so far. It sounds like something rattling in the motor. It is the primary gear is loose on
the right end of the crank shaft. The nut and lock tab are still tight and in place but the gear still gets loose on the spline. If
you remove the clutch side cover, the whole thing not just the small cover, and use an air impact to remove the primary gear nut,
then remove the primary gear from the shaft, it is on a spline, clean it real good and put blue loctite on the spline and replace
the gear, use the air impact to tighten the nut and reset the lock tab. Since I did mine the noise has never come back. Last Sunday
at the track, Chris told Gary his bike sounded strange and Gary panicked. When we got home I tore down Gary's bike and he
had the same problem. After reassembling it everything was OK. The noise does not sound like it's coming from down low, but it is. I
have also seen several of them break the counter-balancer gear that is right behind the primary gear on the shaft. I believe it is
breaking because the primary gear is not tight and it holds the counter-balancer gear tight. When one comes loose, they both get
loose and the counter-balancer gear is much weaker.

Hick

Originally posted by chris thomas:Attached is a reply from a friend about a similar noise.

I have also seen several of them break the counter-balancer gear that is right behind the primary gear on the shaft. I believe it is breaking because the primary gear is not tight and it holds the counter-balancer gear tight. When one comes loose, they both get loose and the counter-balancer gear is much weaker.

Thanks for relaying the info Chris, I can corroborate part of it from personal experience plus I have also heard of others with this problem.

At the risk of being overly repetitive I want to point out that if the bike runs for any length of time with a loose main gear retaining nut the CB (CouterBalancer) drive gear will wear out the straight key that holds it due to the oscillating force placed on that gear by the CB.

I’m afraid that even if the nut is retorqued the rounded key and resultant play in the CB drive gear may be in part causing the gear to break. This play may also contribute to the retaining nut coming loose again and could also end up damaging or ruining the crank

You friend obviously figured this out without any help from me but if he didn’t inspect the key or check for play in the CB drive gear I would encourage him to do so.

You should also make sure that the key does not protrude out from under the CB drive gear, this will lead to a false torque reading on the retaining nut. Eventually the key will wear down and the nut will be loose.

Sorry for boring everyone who has heard me say this 14 million other times, but this can really screw up your bike (it happened to me anyway)…

zack_attack190

Well I have a similar problem. I bought a 00
426 from a friend ( got it cheap ) anyway it has a hinson cluch hub (only). I first thought this was the problem but after taking the cover off the clutch appearded to be ok. so I dug deeper, is it normal for the
clutch to have back and forth play ( I don't mean side to side play ) its like a spacer
is missing. I also noticed rust on the right side crank shaft and gear.

I also found that the nut holding the CB gear down was a little loose.

Hick

The basket will wobble to and fro just a bit, that is a fair amount of leverage you’re talking about. I suppose if the center bushing in the backing plate (or gear plate, whatever) is worn it would wobble some more.

I also found a rust-like substance on my crank, I thought maybe it came from the straight key that got rounded off but I don’t really know what that was. Fiber plate residue? Anyone? (Buehler…..?).

You may want to remove the basket and see if it is properly clearing the case. My stock basket’s rivets that hold the backing plate on were rubbing the case at the rear head bolt boss (the case is raised a bit there where the head bolt threads into the case). I was later unfortunate enough to ruin a case half and noticed on the new ’00 part that I received there is a small notch in the casting in exactly that spot. Hmmm…

They added a plate to the clutch for ’00 but apparently didn’t allow enough clearance (or enough wiggle room for mfg. tolerances) for the thicker clutch.

BTW the Hinson basket made a fairly dramatic improvement in my clutch operation, one of the few mods I’ve made that was worth the $$ (but still a distant second to my Scott’s stabilizer).

426_Monster

Hi ChrisPlease help. Also got this chain noise in the motor. Took it back to the shop and they said it is the Conrod bearing. Fine, I had that done, new conrod cit and crank bearing ,rings (Lots of money later) Still the same noise. Oh yes they also did the CB bearing. They said this noise is normal on al 4 strokes. Hopeefully it is this probleme that you methion with Locktite on the splines.Please give me step by step advise how to do this. I checked the CB gear and it has a little play back/forwards but not side to side. Is it the gear on the cranck that drives the CB gear that needs Locktite if so do you have to pull of the clutch hub to get to it. I also see timing marks on the Drive gear and CB gear. Please help-this noise is driving me mad and I dont trust the bike any more. Please , please will appresiate any help

Originally posted by chris thomas:Attached is a reply from a friend about a similar noise.

I have encountered a problem on two bikes so far. It sounds like something rattling in the motor. It is the primary gear is loose onthe right end of the crank shaft. The nut and lock tab are still tight and in place but the gear still gets loose on the spline. Ifyou remove the clutch side cover, the whole thing not just the small cover, and use an air impact to remove the primary gear nut,then remove the primary gear from the shaft, it is on a spline, clean it real good and put blue loctite on the spline and replacethe gear, use the air impact to tighten the nut and reset the lock tab. Since I did mine the noise has never come back. Last Sundayat the track, Chris told Gary his bike sounded strange and Gary panicked. When we got home I tore down Gary's bike and hehad the same problem. After reassembling it everything was OK. The noise does not sound like it's coming from down low, but it is. Ihave also seen several of them break the counter-balancer gear that is right behind the primary gear on the shaft. I believe it isbreaking because the primary gear is not tight and it holds the counter-balancer gear tight. When one comes loose, they both getloose and the counter-balancer gear is much weaker.

426_Monster

Hi Guys
Batteling with my beast.I did the CB gear thing with the locktite on the splines but the noise are still there.Now I'm clueless. I am sure the noise is on the clutch side.I checked the cluch and plates but all seems well. ANY IDEAS-Please I will try anything!

Ontario_Rider

I had a rattle just like that in my bike.. and it turned out it was the nut on the end of the crank shaft was backing off.. so the mech took off the clutch basket and bent the washer over to prevent this nut from backing off..
This did happen to me.. hopefully for our sake this was a flook..
The bike still rocks though

YZFWrench

Thanks Hick, Chris! My 426 started making a god-awful noise last weekend, and after reading these posts I dug into the clutch side and found the balancer drive gear (under the primary drive gear) loose. After cleaning, lots of lock-tite and tightening-the noise is gone! This sure saved me alota trouble, I hope it does for others as well.

Hick

Just make sure the straight key that holds the CB drive gear (right behind main gear on crank) is not rounded off. If it is chances are the retaining nut may come loose again.

Monster,

I don’t know what loctiting the splines is supposed to do. Check the gear behind the main gear (the CB DRIVE gear) for play. If the CB drive gear, CB shaft or CB gear can be moved, even a tiny bit, independently of the crank then you have rounded off the straight key that holds the CB drive gear in place. This will definitely result in some engine noise.

daveyg

I had this same sound happen with my 426, but couldn't figure it out. I did waste a tranny, had it replaced, and the noise came back a couple weeks later. I sold the beast and am now sitting on the sidelines since I didn't trust her any longer. Considering the 01 426, but may go 2 smoke until the Honda arrives.

Oh, my brothers 426, has the same annoying chain sound when accelerating in 4th gear while the suspension is compressing. Not sure what will come of it.

Hick

I sort of goofed in the reply to your earlier question, the basket will flex side to side a bit due to the way it is connected to the backing plate. The springs behind the basket damp the clutch to shaft connection and the play between the plate and basket will allow you to move the basket from side to side like you described.

If you have a Hinson basket perhaps the allen head fasteners that secure the backing plate have come loose, increasing this play and allowing the basket to rub the cover. If your basket is stock this plate will be secured with rivets. But if the bushing in the plate where it rides on the main shaft is worn this will also allow too much movement and result in the basket rubbing the case. You should also check for contact between the rivets/bolts and case/oil pump drive gear.

My ’00 started blowing water by the pump seal so I replaced the shaft, bearing and seals (the shaft was grooved). But you need a press to R&R the bearing.

I don’t know about the cover, but I think ’00 was the first year for a magnesium clutch cover so maybe they redesigned the part (the part numbers are different for both the engine and clutch covers from ’99 to ‘00). The ’00 clutch has an extra plate vs. ’99 and ’98 so you’d think this mandated a new engine cover at the least (of course the clutch doesn’t really fit in there properly on a lot of ‘00s ).